S1D1 Epson Electronics America, Inc., S1D1 Datasheet - Page 383

• Manufacturer Part Number: S1D1
• Description: LCD Controller-driver With Built-in Character ROM
• Manufacturer: Epson Electronics America, Inc.

S1D15705 Series
Display data latch circuit
The display data latch circuit is a latch that temporarily
stores the display data output from the display data
RAM to the liquid crystal drive circuit.
Since the Display Normal Rotation/Reversal, Display
ON/OFF, and Display All Lighting ON/OFF commands
control the data in this latch, the data within the display
data RAM is not changed.
Oscillator Circuit
This oscillator circuit is a CR type oscillator and generates
display clocks. The oscillator circuit is valid only when
M/S=HIGH and CLS=HIGH and starts oscillation after
the Built-in Oscillator Circuit ON command is entered.
When CLS=LOW, the oscillation is stopped and the
display clocks are entered from the CL pin.
Display Timing Generator Circuit
This display timing generator circuit generates timing
signals from the display clocks to the line address circuit
and the display latch circuit. It latches the display data
to the display data latch circuit and outputs it to the
segment drive output pin by synchronizing to the display
clocks. The read operation of display data to the liquid
crystal drive circuit is completely independent of the
access to the display data RAM from the MPU. Therefore
2-frame alternating current drive waveforms
10–24
Master (M/S=HIGH) Built-in oscillator circuit valid (CLS=HIGH) Output
Slave (M/S=LOW) Built-in oscillator circuit valid (CLS=HIGH)
COM0
COM1
SYNC
DATA
SEGn
RAM
FR
CL
Operation mode
64
Built-in oscillator circuit invalid (CLS=LOW) Output
Built-in oscillator circuit invalid (CLS=LOW)
65 1
2
3
4
5
6
EPSON
Table 5
Fig. 5
60 61 62 63 64 65 1
even when the display data RAM is asynchronously
accessed during liquid crystal display, the access will
not have any adverse effect on the display such as
flickering.
The circuit also generates the internal common timing,
liquid crystal alternating current signal (FR), and
synchronous signal (SYNC) from the display clocks.
As shown in Fig. 5, the FR normally generates the drive
waveforms in the 2-frame alternating current drive
system to the liquid crystal drive circuit. It can generate
n-line reversal alternating current drive waveforms by
setting data (n-1) to the n-line reversal drive register. If
a display quality problem such as crosstalk occurs, it
can be improved by using the n-line reversal alternating
current drive waveforms. Determine the number of
lines (n) to which alternating current is applied by
actually displaying the liquid crystal.
SNYC is a signal that synchronizes the line counter and
common timing generator circuit to the SYNC signal
output side IC. Therefore the SYNC signal becomes a
waveform at a duty ratio of 50% that synchronizes to the
frame synchronization.
When the S1D15705 series is used for the multiple chip
configuration, the slave side needs to supply the display
timing signals (FR, SYNC, CL, and DOF) from the
master side.
Table 5 shows the state of FR, SYNC, CL, or DOF.
Input
Input
FR
Output
SYNC
Output
Input
Input
2
3
4
5
Output
Input
Input
Input
CL
6
V
V
V
V
V
V
V
V
V
V
V
V
Rev. 3.1a
Output
Output
DD
1
4
5
DD
1
4
5
DD
2
3
5
DOF
Input
Input